[ncl-talk] How to specify the unit of wind speed in `skewT_PlotData`

[李嘉鹏]

Hi, I am trying to figure out the wind speed unit used by the `skewT_PlotData` function, [the documentation page] (http://www.ncl.ucar.edu/Document/Functions/Skewt_func/skewT_PlotData.shtml) and the [skewT example page] (http://www.ncl.ucar.edu/Document/Functions/Skewt_func/skewT_PlotData.shtml) says the unit of the wind speed is either knot or m/s, but they are not the same: $ udunits2 udunits2: Using default XML database You have: knot You want: m/s 1 knot = 0.514444 m/s x/(m/s) = 0.514444*(x/knot) If I pass float values to the `WSPD` (`u`) and `WDIR` (`v`) argument, how do I know or control the way `skewT_PlotData` interpret these values? [The WMAP documentation on wind barbs] (http://www.ncarg.ucar.edu//supplements/wmap/index.html#HEADING1-140) indicates that the unit is knot, and [The WMAP documentation on station data] (http://www.ncarg.ucar.edu//supplements/wmap/index.html#HEADING1-151) mentioned a property called `UNT`, but it's not available for the `WMBARB` function. I tried to get these information from the source code `ni/src/examples/gsun/skewt_func.ncl`, the function `skewT_PlotData_Original` or `skewT_PlotData_Panel` does not perform unit conversion, and the properties set for the `WMBARB` function (WDF, COL, WBA) are not related to wind speed units. I'll be grateful if someone can provide the exact information. --- Regards
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